According to Quality Computers, who makes AppleWorks 4.0, Version 4.0 Word Processing documents have the same file format as AppleWorks 3.0.
This means that converting AppleWorks 4.0 files into ClarisWorks files should be no problem using the regular AppleWorks translator (provided with ClarisWorks), along with Apple File Exchange, or PC Exchange 2.0 which now handles ProDOS as well. PC Exchange 2.0 ships with system 7.5.